The present invention relates to a device for ascertaining distance and transmitting data in a motor vehicle.
A system for measuring distance and the selective transmission of information for motor-vehicle applications is described in German Published Patent Application No. 44 42 189. The transmitting and receiving units provided for the distance measurement are at the same time used for transmitting and receiving information and/or the signals used for the distance measurement are utilized directly for the transfer of information. With the aid of the distance measurement, passive protective measures for vehicles can be activated in response to a front, side or rear collision. The information exchange is used for assessing traffic situations, or for detection, identification and cost allocation for a road toll.
An object of the present invention is to develop the transmission channel, present for the distance measurement, for further motor-vehicle functions which are only activated in conjunction with a data exchange deemed as valid.
The device for ascertaining distance and transmitting data in a motor vehicle has a transmission arrangement for generating and emitting a radar signal. It is equipped with a receiving arrangement for the reception of a radar signal for detecting the distance and/or the speed of a further object. The device of the present invention has the distinction that a switchover arrangement are provided which cause the transmitting and/or receiving arrangement to operate either in a radar operating mode for determining distance and/or speed of the further object, or in a data-exchange operating mode for the data exchange with a transceiver, specific motor-vehicle functions being enabled as a function of the data exchange. These motor-vehicle functions can be a master-key system or the cancellation of a vehicle immobilizer. According to the present invention, the transmitting and receiving arrangement, present anyway for ascertaining the distance or speed, are also used for the purpose of exchanging data with an optionally portable transceiver. The data exchange with the transceiver is evaluated for an authorization. If the receiving arrangement receives a data signal, recognized as valid, from the transceiver, then, for example, the master-key system is activated along the lines of unlocking. If the data exchange proceeds within the motor vehicle, then it can be utilized to query the driving authorization of the user with the aid of the transceiver carried along. The start enablement is only granted in response to a transceiver signal recognized as authorized. By integrating the additional function of the data exchange for the purpose of the access authorization and start authorization, existing components which are already provided for implementing other functions can likewise be utilized. With the aid of the switchover arrangement, the different operating modes of the transmitting and receiving arrangement can be specifically selected depending on the operating situation. In the radar operating mode, the distance and/or the speed of the vehicle with respect to an adjacent object is/are ascertained. These data can be utilized for triggering an airbag, for controlling a warning device in connection with a Park Pilot system, detection of objects in the so-called dead angle, and stop-and-go detection. An emission of the radar signal into the passenger compartment of the motor vehicle can be evaluated for the purpose of monitoring the passenger compartment in conjunction with a car alarm or a seat-occupant detection.
In one expedient refinement, the data-exchange operating mode is activated when the motor vehicle has been switched off and/or the user has left the motor vehicle. At this point, the transmitting and receiving arrangement are controlled, such that they are able to send and/or receive and evaluate a data signal. Namely, to unlock the master-key system, an appropriate data signal is expected from the transceiver.
In another refinement, the data-exchange operating mode is activated when a switching element has been actuated, for example, in conjunction with the initiation of an unlocking operation and/or start of the motor vehicle. For instance, upon actuation of the ignition switch, a switchover is made to the data-exchange operating mode. In order for the enablement to be granted for starting the motor vehicle, it is necessary for the transmitting and receiving arrangement and the transceiver to have run through a data exchange recognized as valid. If the data exchange is to be evaluated for the purpose of unlocking the motor vehicle, the user, for example, actuates the door handle of the motor vehicle. The switching signal recognized in this connection brings about a switchover into the data-exchange operating mode, so that data can now be exchanged with the transceiver. If the data exchange is run through successfully, the master-key system is activated along the lines of unlocking.
In one advantageous refinement, the switchover arrangement is controlled in the manner that they are used for information coding. Thus, a dual function is ensured. First of all, the switchover can consequently be implemented; on the other hand, in the data-exchange operating mode, the switchover arrangement are used as a modulation arrangement.